Research On The Application Of FeCl₃ In The Free Radical Polymerization Of Electron-Deficient Olefin

The discovery of atom transfer radical polymerization?ATRP?and reversible addition-fragmentation chain transfer polymerization?RAFT?provides a new way for accurate synthesis of functional polymers such as block,graft and hyperbranched polymers,but both methods usually require the introduction of expensive ligands and a large number of volatile organic solvents,meanwhile the polymerization temperature is high,transition metals are difficult to remove,and the polymerization conditions are harsh.It greatly limited its application in industrial production.In order to solve this problem,this work uses two kinds of economic and environmentally friendly raw materials,namely H₂O₂ and FeCl₃,and successfully developed a new free radical polymerization method with simple in preparation process and environmentally friendly.H₂O₂ and FeCl₃ were applied to the polymerization of acrylonitrile,methacrylic acid and other monomers,by using the bi-directional reversible cycle regeneration of Fe³⁺-Fe²⁺during the chain growth process,the continuous redox initiation of H₂O₂/FeCl₃ can be realized and the free radical polymerization of acrylonitrile,thus acrylic acid and other monomers in aqueous solution can be initiated.The continuous precipitation polymerization of acrylonitrile in water was successfully carried out by using PEG4000/ammonium cerium nitrate/FeCl₃ system,and the PAN-PEG-PAN block polymer with clear structure and controllable structure was synthesized.When the polymerization of methacrylic acid initiated by H₂O₂/FeCl₃,the molecular weight of sodium polyacrylate was between 1.0×10⁶-2.0×10⁶ g/mol at lower initiator concentration and lower reaction temperature?30?-60??,and the molecular weight of sodium polyacrylate was in the range of 1.0×10⁶-2.0×10⁶ g/mol.The molecular weight of sodium methylacrylate ranged from 1.0×10⁵-1.7×10⁵ g/mol with lower molecular weight distribution?M_w/M_n=1.1-1.4?and better conversion rate?>90%?.The polymerization of acrylonitrile was initiated by using H₂O₂/FeCl₃ as initiator system.When the molar ratio of[AN]₀/[FeCl₃]₀/[H₂O₂]₀=100:0.4:10,the acrylonitrile conversion reached the highest value in 60min at 60?.The highest conversion rate of acrylonitrile was 94.1%;When the dosage of FeCl₃ and H₂O₂ was changed,the molecular weight of polyacrylonitrile was controll ed in the range of 2.0×10⁴-8.0×10⁴ g/mol.The continuous precipitation polymerization of acrylonitrile in water was carried out by using PEG4000/ammonium cerium nitrate as initiator and FeCl₃ as chain transfer agent.The PAN-PEG-PAN block polymer with clear structure and controllable molecular weight was synthesized and molecular weight is 1.0×10⁴-4.5×10⁴;When the molar ratio of raw material[AN]₀/[PEG 4000]₀/[FeCl₃]₀/[Ce⁴⁺]₀=300/3/3/2,the molecular weight of 40 min block polymer was 1.69×10⁴ g/mol at 35?,the conversion of acrylonitrile was up to 83.7%.